1,636 research outputs found

    Robust Adaptive Control

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    Several concepts and results in robust adaptive control are are discussed and is organized in three parts. The first part surveys existing algorithms. Different formulations of the problem and theoretical solutions that have been suggested are reviewed here. The second part contains new results related to the role of persistent excitation in robust adaptive systems and the use of hybrid control to improve robustness. In the third part promising new areas for future research are suggested which combine different approaches currently known

    Kinetic energy functional for Fermi vapors in spherical harmonic confinement

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    Two equations are constructed which reflect, for fermions moving independently in a spherical harmonic potential, a differential virial theorem and a relation between the turning points of kinetic energy and particle densities. These equations are used to derive a differential equation for the particle density and a non-local kinetic energy functional.Comment: 8 pages, 2 figure

    Metastable states of a ferromagnet on random thin graphs

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    We calculate the mean number of metastable states of an Ising ferromagnet on random thin graphs of fixed connectivity c. We find, as for mean field spin glasses that this mean increases exponentially with the number of sites, and is the same as that calculated for the +/- J spin glass on the same graphs. An annealed calculation of the number <N_{MS}(E)> of metastable states of energy E is carried out. For small c, an analytic result is obtained. The result is compared with the one obtained for spin glasses in order to discuss the role played by loops on thin graphs and hence the effect of real frustration on the distribution of metastable states.Comment: 15 pages, 3 figure

    Limit Cycles of Planar Quadratic Differential Equations

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    Since Hilbert posed the problem of systematically counting and locating lhe limit cycle of polynomial systems on the plane in 1900, much efTort has been expended in its investigation. A large body of literature - chiefly by Chinese and Soviet authors - has addressed this question in the context of differential equations whose field is specified by quadratic polynomials, In this paper we consider the class of quadratic differential equations which admit a unique equilibrium state, and establish sufficient conditions, algebraic in system coefficients, for the existence and uniqueness of a limit cycles. The work is based upon insights and techniques developed in an earlier analysis of such systems [1] motivated by questions from mathematical control theory

    Neural Modeling and Control of Diesel Engine with Pollution Constraints

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    The paper describes a neural approach for modelling and control of a turbocharged Diesel engine. A neural model, whose structure is mainly based on some physical equations describing the engine behaviour, is built for the rotation speed and the exhaust gas opacity. The model is composed of three interconnected neural submodels, each of them constituting a nonlinear multi-input single-output error model. The structural identification and the parameter estimation from data gathered on a real engine are described. The neural direct model is then used to determine a neural controller of the engine, in a specialized training scheme minimising a multivariable criterion. Simulations show the effect of the pollution constraint weighting on a trajectory tracking of the engine speed. Neural networks, which are flexible and parsimonious nonlinear black-box models, with universal approximation capabilities, can accurately describe or control complex nonlinear systems, with little a priori theoretical knowledge. The presented work extends optimal neuro-control to the multivariable case and shows the flexibility of neural optimisers. Considering the preliminary results, it appears that neural networks can be used as embedded models for engine control, to satisfy the more and more restricting pollutant emission legislation. Particularly, they are able to model nonlinear dynamics and outperform during transients the control schemes based on static mappings.Comment: 15 page

    Low current Cd4+T cell count: prediction, for persistent herpetic gingivostomatitis in HIV-positive patients under antiretroviral therapy

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    Background: Oral viral lesions associated with HIV infection are important since they affect the quality of life of the patient and are useful markers of disease progression and immunosuppression. The purpose of this study was to correlate the persistence of herpetic gingivostomatitis lesions with the current CD4+ T cell count for adherence of HIV-infected individuals to anti retroviral therapy (ART) and antiviral therapy.Methods: 302 HIV +ve patients developing oral ulcers were included in this study. The herpes simplex viral infections associated with the oral manifestations were detected through Immuno histochemical staining. The quantitative analysis of oral ulceration was done by using mucositis index.CD4T cell count was correlated with clinical manifestations of extensiveness of oral ulcers, acute febrile condition and other constitutional symptoms during follow up of cases for the treatment with anti viral therapies.Results: Association of herpes simplex viral infections was found in 72 out of 302 HIV+ ve cases. All the HSV +ve patients developed extensive oral mucsal lesions during the 1st week. Extensive lesions developed within 7 days in patients with CD4 count 500, manifestation of mucosal ulcers due to acute herpetic gingivostomatitis was limited to a period of 1 to 2 weeks. Patients with CD4 count >200 <500 did not follow a definite pattern.Conclusions: Persistent oropharyngeal mucosal ulcers along with acute febrile condition due to herpes simplex virus infection are associated with low CD4 T cell count in HIV + patients under antiretroviral therapy

    A huge right staghorn renal calculi: a case report of inevitable open surgery

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    Staghorn renal calculi in a developing country, very often associated with insidious growth, late presentation, complication &amp; recurrence, present an economic burden to the patient &amp; challenge to the treating surgeon. A 70 years old male patient presented to the surgery dept. of our medical college with chief complaints of intermittent pain in right side of abdomen since 4 years, with increased frequency for last 5 days &amp; radiating to back, non-radiating to groin, had h/o intermittent low grade fever and 3-4 times hematuria. Right sided pyelolithotomy done and a huge staghorn calculi that is extending into renal calyces is removed. Post operatively patient uneventful. In the last few decades, with improvement in endourological surgery, the indications for open surgery in stone diseases have become rare, although open surgery still has a role in selected cases such as complex stone burden, renal anatomic complications

    Effect of nano and macro iron sprays on growth, flowering, seed and oil yielding attributes in calendula (Calendula officinalis L.)

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    The investigation was executed with nine treatments viz. nano forms of ferrous sulfide (7, 14, 21, 28 ppm) and macro ferrous sulphate (0.2, 0.4, 0.6, 0.8 per cent) along with control, and were applied as foliar sprays after 30 days of transplanting on two varieties of calendula namely Fiesta Gitana Mix’ and ‘Fiesta Yellow’ during 2018 and 2019. The experiment was laid out in factorial randomized block design with three replications. Application of 0.8 % FeSO4 recorded maximum number of branches (26.75), plant height (29.73 cm), plant spread(45.17 cm), number of leaves (22.63) and seed test weight (15.63 g) and number of flowers per plant (134.04). However, application of 0.2% macro FeSO4 resulted in early bud appearance (50.50 days) and higher flower diameter (8.09 cm). ‘Fiesta Gitana Mix’ outperformed over ‘Fiesta Yellow’ for most of the vegetative and floral characters. The ‘Fiesta Yellow’ variety with oil content (13.97%) had an edge over ‘Fiesta Gitana Mix’

    Combining Ability Studies in Cowpea for Dual Purpose Types

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    Cowpea (Vigna unguiculata (L) Walp.) is widely grown all over India more particularly in central and peninsular regions. Grains are consumed as food and the haulms are fed to livestock as a nutritious fodder. Cowpea is is equally important as nutritious fodder for livestock. The use of cowpea as a dual-purpose crop is attractive in mixed crop/livestock systems where land and feed are becoming increasingly scarce (Tarawali et al., 1997) especially in the dry season. Efforts at global level (IITA & ILRI) focused to develop medium-maturing (85-95 days), semi-erect, dual-purpose varieties with higher grain and fodder yields and with enhanced fodder quality
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